Electric organs have evolved independently several times. Among aquarium fish, Mormyrids and Gymnotiformes would be the most commonly found examples. There are also electric catfish and torpedos and some ray-like things.

The electricity generating cells are evolved from muscle cells, losing their ability to contract, changing their shape, and putting the ion channels on particular surfaces to direct the current flow. Genome analysis showed changes in genes involved in transcription control, cell size, excitation, contraction, and insulation (for around the electric organ).

The goal of my title was to get a lot of electricity associated words into a single sentence. Any got more?